Communication systems are known to support wireless and wired communications between wireless and/or wired communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), and/or variations thereof.
Depending on the type of wireless communication system, a wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, and/or home entertainment equipment, communicates directly or indirectly with other wireless communication devices. For direct communications, also known as point-to-point communications, the participating wireless communication devices tune their receivers and transmitters to the same channel, or channels, such as one or more of the plurality of radio frequency (RF) carriers of the wireless communication system, and communicate over that channel(s). For indirect wireless communications, each wireless communication device communicates directly with an associated base station for use of cellular services, for example, and/or an associated access point for use of an in-home or in-building wireless network, for example, via an assigned channel, or channels. To complete a communication connection between the wireless communication devices, the associated base stations and/or associated access points communicate with each other directly, via a system controller, via the public switch telephone network, via the internet, and/or via some other wide area network.
For each wireless communication device to participate in wireless communications, it may include a built-in radio transceiver comprising a receiver and transmitter, or it may be coupled to an associated radio transceiver, such as a station for in-home and/or in-building wireless communication networks, and/or an RF modem. The transmitter may be adapted to convert data into RF signals by modulating the data in accordance with the particular wireless communication standard to produce baseband signals and mixes the baseband signal with a local oscillator signal in one or more intermediate frequency stages to produce the RF signals. The radio receiver may include an antenna section, a filtering section, a low noise amplifier, an intermediate frequency (IF) stage, an equalization stage, and/or a demodulator. The antenna section may receive RF signals and may provide them to the filtering section, which, in turn, may pass RF signals of interest to the low noise amplifier (LNA).
The LNA may amplify the received RF signals of interest and may provide them as amplified RF signals to the IF stage. The IF stage may step down the frequency of the RF signals of interest to an intermediate frequency or to baseband. The IF stage may then provide the intermediate frequency signals, or baseband signals, to the equalization stage. The equalization stage may add loss or delay to specific frequencies to produce a flat frequency response. The equalization stage may then output an in-phase (I) and/or a quadrature (Q) component to the demodulator. The demodulator may be adapted to synchronize the signal and/or to recapture the data in accordance with a demodulation protocol.
In conventional RF transceivers, for the demodulator to accurately recover data from IF signals or baseband signals, DC offsets may need to be overcome. DC offsets in a demodulated output may result when the clock circuitry of a transmitting radio produces a slightly different clock rate than the clock rate produced by the receiving radio. The local oscillation within the transmitting radio, therefore, may not produce the exact same rate of oscillation as the rate produced by the local oscillation in the receiving radio. In addition, the RF transceiver may need to account for a phase offset during demodulation, time error detection, vector-to-angle conversion, vector-to-amplitude conversion, and/or vector rotation, for example. The conventional RF transceiver, therefore, may need to utilize a plurality of separate circuits, such as a DC offset compensation circuit, a phase offset compensation circuit, and other circuitry necessary for signal synchronization and/or demodulation. Consequently, a large number of circuits may be required for implementing a conventional RF transceiver, which may increase production costs and decrease efficiency. Additionally, a large number of circuits require a much larger silicon and increases power consumption.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.